1. Field of the Invention
An embodiment of the present invention relates to a semiconductor device including a transistor or a semiconductor device including a circuit which is formed by using a transistor. For example, an embodiment of the present invention relates to a semiconductor device including a transistor in which a channel formation region is formed using an oxide semiconductor or a semiconductor device including a circuit which is formed by using such a transistor. Further, the present invention relates to an electronic device which includes, as a component, an LSI, a CPU, a power device mounted in a power circuit, a semiconductor integrated circuit including a memory, a thyristor, a converter, an image sensor, or the like, an electro-optical device typified by a liquid crystal display panel, or a light-emitting display device including a light-emitting element.
In this specification, a semiconductor device means all types of devices that can function by utilizing semiconductor characteristics, and an electro-optical device and a semiconductor circuit are both semiconductor devices.
2. Description of the Related Art
In recent years, semiconductor devices have been developed to be used as an LSI, a CPU, or a memory. A CPU is an aggregation of semiconductor elements each provided with an electrode which is a connection terminal, which includes a semiconductor integrated circuit (including at least a transistor and a memory) separated from a semiconductor wafer.
A semiconductor circuit (IC chip) of an LSI, a CPU, or a memory is mounted on a circuit board, for example, a printed wiring board, to be used as one of components of a variety of electronic devices.
Further, a technique for using an oxide semiconductor for a channel formation region in a transistor has been attracting attention. Examples of such a transistor include a transistor in which zinc oxide (ZnO) is used as an oxide semiconductor and a transistor in which InGaO3(ZnO)m is used as an oxide semiconductor. A technique for manufacturing such a transistor including an oxide semiconductor over a light-transmitting substrate and applying it to a switching element or the like of an image display device is disclosed in Patent Documents 1 and 2.